Artificial denture and retaining means therefor



June 7, 1966 R. FUST 3,254,410

ARTIFICIAL DENTURE AND RETAINING MEANS THEREFOR Filed Jan. 16, 1963Robert F ust 3 N VE N TOR United States Patent O F 35,8 14 Claims. c1.32-5 The invention relates to a device for elastically connectingpartial artifical dentures with the remaining natural teeth or with eachother.

It is known to construct especially partial, but also complete,artificial dentures, particularly those made of plastics, in one piece.They are supported on the mucous membrane or gum and the partialdentures are detachably anchored to the remaining natural teeth by meansof olasps. Experience shows that these artificial dentures have atendency to damage the remaining natural teeth,

in particular those serving as anchors because the mucous membrane ofthe jaw yields with any chewing pressure exerted on the artificialdenture. As this occurs, tilting movements of the artificial denture arecreated which are transferred to the anchor teeth through the connectingclasps.

Very often the remaining natural teeth are constituted .by the incisorsand the individual bicuspids so that the molars must be replaced byso-called free saddles, the artificial denture then having its endfreely supported on the alveolar ridge of the edentated jaw portion.Here the free saddles are depressed especially during the chewing actionowing to the yielding character of the mucous membranes, and thistilting movement is resisted solely by the incisors of the remainingnatural teeth, in particular, the teeth carrying the clasps. Thesestresses lead to a loosening of the anchor teeth. In addition, theseteeth are damaged by the friction of the clasps to such an extent thatpain is caused by the exposed dentine. Furthermore, the incidence ofcaries in such teeth is high.

In many cases, the loss of the molars is confined to one side so thatholders may be fitted to the remaining natural teeth at which the freeend saddles are connected with joints. Mostly, steel plates are used forthis purpose. The result of this pivotal connection is that the free endsaddles may swing away at their ends but not at the point of connectionto the artificial denture or crown to which they are attached.

It has been found that a substantial percentage of patients decline towear an artificial denture made in one piece because the aforedescribedphenomena are disturbing to a point where the patients forego toothreplacement rather than have their remaining natural teeth destroyed. Inaddition, a replacement with pivotable connections at themetal plates isrelatively expensive and is therefore out of the question for broadstrata of the people. Furthermore, when designing the teeth in case of areplacement on a free end saddle which is pivotally connected with asteel plate or a crown, one has to take into consideration the effectsof the chewing pressure because this free end saddle can press itselfonly into one end of the deformed mucous membrane. It is thereforenecessary that the last molars be made smaller so that the chewingpressure is relieved at this location.

In order to avoid these disadvantages, and in accordance with theinvention, I provide a fastening device for partial artificial denturesmade of plastics in which the connection between the artificial teethand the remaining natural teeth is made resilient so that the chewingpressure effective, for instance, on one free end saddle cannot betransferred to the remaining natural teeth. In accordance with theinvention, a guiding pin made of spring wire and fastened to theremaining natural teeth 3,254,410 Patented June 7, 1966 projects forthis purpose into the artificial denture and is enclosed adjacentthereto by a sleeve which may be embedded in the artificial denture, acoil spring being disposed in the space between the guiding pin and thesleeve and tensioned between an abutment on the sleeve and an abutmenton the guiding pin, with at least one pair of coacting formations beingprovided on the sleeve and on the guiding pin to prevent a relaxation ofthe spring.

An extension of the pin extending endwise from the sleeve,

such as a spring wire integral with that pin, is thus limitedly movablein outward direction against the spring force, this extension beinganchored to an external support such as a natural tooth or anotherpartial denture.

In a preferred embodiment of the invention two such spring guides areembedded in the artificial plastics denture in such a manner that thesleeves provided with stressed springs are disposed laterallly along theridge on both sides thereof. One end of the spring-guiding pins isarranged to embrace the remaining natural teeth in a manner known per seor to be fastened with an intermediate piece of a plastic materialserving to anchor 'the partial artificial denture to the remainingnatural teeth. It the molars are to be replaced on both sides, it isproposed that the spring pin constitute a terminal portion of a flexibleelongated tension element, such as a wire, extending lingually behindthe incisors from one spring sleeve, embedded in one partial denture, toanother spring sleeve, embedded in the other partial denture, theintermediate portion of the guide wire being embedded in a plastic armoror sheath separating the two partial artificial dentures in which thepin-shaped extremities of the wire are concealed. This plastic armor isthen secured to the remaining natural teeth with the aid of arcuateolasps which are likewise embedded in the plastic armor and the freeends of which detachably surround the residual natural teeth.

I further propose. particularly in connection with smallor partialartificial dentures, to connect two approximately parallel guide pins,encased in coil springs and sleeves, with metallic tooth crowns byattaching to said crowns a releasable holding device for the guidingpins. By virtue of this flexible and resiliently yieldable linkagebetween the remaining natural teeth and the partial artificial denture,the force exerted under pressure, e.g. during chewing, is nottransmitted to the remaining natural teeth through the connecting pieceproper because the artificial denture is movable within certain limitswith respect to its holding arrangement. The coil spring compressedbetween the sleeve and the guide pin allows for an elastic axialdisplacement between the guide pin and the sleeve and thus between theartificial denture and its support in a manner permitting limitedseparation of the denture from the support against its biasing force,this force being inwardly directed with reference to the tooth carrierin which the sleeve is embedded.

The stored force of the stressed spring is absorbed by its end stops sothat no stresses are exerted on the partial artificial denture and theremaining natural teeth. In order to permit adaptation to therequirements of a complete artificial denture, the sleeve is providedwith a certain clearance with respect to the guiding pin which isdetermined by the resiliency of the mucous membranes. It has proved tobe advantageous to make the inner diameter of the sleeve 2 mm becausethe resiliency of the mucous membrane allows it to yield by about 0.7 to1 mm. In this manner, the partial artificial denture is rendered freelymovable in any direction within the limits desired, without being undulyloosely seated on the ridge. Therefore, the patient when chewing has theimpression of biting on his own teeth.

The invention may also serve to improve the fastening of a fullartifical denture in that the denture is made of 0 several parts whichare elastically interconnected. Thus, the complete denture may be madeof three parts, the middle one of which is fastened in a manner knownper se by a suction press-fit onto the corresponding alveolar ridge ofthe jaw. This middle portion serves to secure the guiding pins whoseends are then again provided with the aforementioned abutments and coilsprings for elastically holding two partial artificial dentures carryingthe replacement for the molars and under certain circumstances, also forthe premolars.

Further features and details of the invention will be described withreference to the accompanying drawing in which:

FIG. 1 shows by way of example a retaining device consisting of a springguiding pin, a coil spring and a sleeve for elastically connectingpartial artifical dentures with the remaining natural teeth;

FIG. 2 is a top plan view of a three-part dental prosthesisincorporating two partial dentures each provided with a pair ofretaining devices as shown in FIG. 1, the plastic carrier of eachpartial denture and the artificial teeth fastened :thereon being shownin dot-dash lines;

FIG. 3 is a sectional view taken on line III-III of FIG. 2;

'FIG. 4 is a partial sectional view taken on line IVIV of FIG. 3; and

FIG. 5 shows a sectional view of a modified retaining 'device for apartial denture fastened to a metal crown.

The unit shown in FIGS. 1-4 comprises a set of spring- -guiding pins 1or bolts each formed of a wire and connected on one side with theremaining natural teeth 12 or a part of a complete artificial denture,its free end on the other side being secured in a manner to be describedhereinafter, to the plastic carrier 23 or 24 of a partial artificialdenture 21 or 22. The free end of each pin carries a coil spring 3 whichis .tensioned between an abutment 4, constituted by a nut and adjustablevia a thread 2, and a restriction 6 of a sleeve 5. In this arrangement,one end of the sleeve 5 is closed by a slotted set screw 7 against whichone extremity of the guide pin 1 abuts. The sleeve 5 is embeddedin theplastic carrier 23 or 24 of the artificial denture and is rigidlyconnected therewith. By selection of the spring tension it is possibleto support the horizontally disposed sleeve 5 and with it the artificialdenture 21, 22 for limited, resiliently restrained motion in an axialdirection with respect to the pin :1. The all-around lateral clearanceprovided by the sleeve 5 around the pin 1 and the spring 3 enables aradial movement of the sleeve and thus simultaneously of the artificialdenture with respect to the pin 1. The embodiment illustrated by way ofexample shows an artificial denture consisting of three parts in a casewhere the molars are missing on both sides but a central remainder ofthe natural teeth 12 is available. The curved middle portion of theartificial denture is a plastic sheath 8 which is positioned behind theincisors 1-2. The tip of the threaded screw 7 and the left-hand endportion 2 of the pin 1 form a pair of abutments preventing a relaxationof the spring 3.

In accordance with FIGS. 2 and- 3, two pairs of springguiding pins 1,provided on their free ends with springs 3 and sleeves 5, are enbeddedin different partial artifical dentures 21, 22. The sleeves 5 arerespectively arranged in pairs on both sides of the ridge 11 in adownwardly concave plastic carrier .23, 24 for the artificial denture,this carrier straddling the alveolar ridge of the jaw (see FIG. 4) in amanner known per se to retain the artificial teeth 25, 26. Theintermediate portions of the springguiding wires extend lingually behindthe remainder of .the natural teeth 1-2 and are embedded in the plasticarmor or sheath 8. At the same time, retaining clasps are embedded inthis plastic armor S and detachably enclose with their ends theremainder of the natural teeth 12 or parts thereof. FIG. 2 shows theseveral retaining devices for the partial dentures 21, 22 in differentmounting stages. At the top, there is shown a guide pin 1 provided withthe end thread 2 and without any additions. The next-lower pin 1 isprovided with a spring 3 and the rear spring abutment 4 designed as anut. In the upper half of the lower pair, the spring 3 is alreadysurrounded by the sleeve 5 shown in section and closed on one side bythe set screw 7; and on the very bottom, there is finally shown anelevational view of the complete sleeve mounted on the one end of thepin 1. Interposed between the remainder of the natural teeth 12 and thetwo partial artificial dentures are layers 9 of a plastic material whichremains soft. Through these plastic layers 9, the pins 1 are guided. Thepins 1, the springs 3 and the sleeve 5 are shown on an enlarged scalerelative to the denture for the sake of clarity. It will be apparentthat the mobility of the wire elements 1 in their sleeve 5 is increasedby the fact that the constriction 6 is spaced to a considerable extent,i.e. .by more than one-third the length of the sleeve, from the open endof the latter which faces the anchor clamp 10.

FIG. 5 shows the elastic retaining means for a partial denture fastenedto a metal crown 20. The crown 20 which is to be fastened .to a toothhas soldered thereto a U-shaped yoke or journal bearing 13 which isenclosed by a second, oppositely facing U-shaped yoke or journal bearing14. The two yokes are provided with aligned holes 15, 16 through which ascrew or journal pin .17 is inserted for the connection of the yokes. Onyoke 14 there are provided two substantially parallel guide pins 1having connected to the -free ends thereof coil springs 3 and sleeves 5in accordance with FIGS. 13. The face 27 of the-yoke 14 and the edges 28of the sleeves 5 may serve as co-operating abutments for limiting therelaxation of the springs 3. It will be noted that the assembly 13-17constitutes a hinge by which the projecting portions of pins 1 arepivotally linked with the anchor member 20, the pivotal axis of thehinge being perpendicular to the spring housings or sleeves 5.

In order to make possible an easy replacement of the coil springs,particularly in the case of fatigue phenomena,

the sleeves 5 are provided with lateral bores 19, instead of therestriction 6, in which screws 18 are inserted in a radial direction.The springs 3 are clamped between the adjustable abutments 4 and thescrews 18. The two sleeves 5 are then again embedded in a plasticdenture carrier conforming to the alveolar ridge and having the falseteeth fastened thereto, as explained in connection with the embodimentof FIGS. 14. If it is intended to replace the coil springs 3, one needonly loosen the screws 18 which, incidentally, also serve the purpose ofassisting in keeping the sleeves 5 in the plastic carrier of theartifical denture, the guide pins 1 may thus be withdrawn together withthe springs 3 from the plastic carrier.

What I claim is:

1. A resilient unit for yieldably attaching a partial denture to asupport element of a human jaw, comprising, in combination, a journalassembly including a journal pin, a first journal bearing and a secondjournal bearing, means for connecting said first bearing to said supportelement, at least one bolt substantially transverse to said journal pinconnected to said second bearing, a first stop member provided on saidbolt, a tubular member encircling with clearance said bolt and providedwith a second stop member, a helical spring bearing on said first andsecond stop members and arranged in said clearance between said bolt andsaid tubular member, said bolt and said tubular member being providedwith coacting formations for placing said spring under stress, saidtubular member being adapted to be connected to said partial denture.

2. A resilient unit for yieldably attaching a partial denture to asupport element of a human jaw, comprising, in combination, a journalassembly including a journal pin, a first journal bearing and a secondjournal bearing, means for rotatably supporting said bearings on saidpin, a metal crown connected to said first bearing and adapted to beattached to a .natural tooth of said human jaw, two bolts connected tosaid second bearing and extending substantially transverse to saidjournal pin and mutually parallel, threaded portions provided on saidbolts, two nuts screwed onto said threaded portions and forming firststop members, two sleeves encircling with clearance said bolts andprovided with second stop members, two coil springs each bearing on saidscrew nuts and said second stop members and arranged in a respectedclearance bet-ween said bolts and said sleeves, said bolts and saidsleeves being provided with coacting formations for placing said springsunder tension, and sleeves being adapted to be connected to said partialdenture.

3. A partial denture comprising a downwardly concave tooth carrierfitting 'over the alveolar ridge of an edentated jaw portion, anelongated flexible element projecting endwise from said carrier forattachment to an external support on the jaw, spring means in saidcarrier engaging said element with an inwardly directed biasing force,and abutment means rigid with said carrier maintaining said spring meansunder stress by limiting the inward displacement of said element by saidbiasing force, the projecting portion of said element being withdrawablefrom said carrier against said biasing force for enabling said abutmentis positioned intermediate the ends of said limited yielding of saidcarrier to a force tending to separate it from said support.

4. A partial denture comprising a downwardly concave tooth carrierfitting over the alveolar, ridge of an edentated jaw portion, a pair ofsubstantially parallel elongated flexible elements projecting endwisefrom said carrier at locations corresponding to opposite sides of saidridge for attachment to an external support on the jaw, spring means insaid carrier engaging said elements with an inwardly directed biasingforce, and abutment means rigid with said carrier for maintaining saidspring means under stress bylimiting the inward displacement of saidelements by said biasing force, the projecting portions of said elementsbeing withdrawable from said carrier against said biasing force forenabling limited yielding of said carrier to a force tending to separateit from said support.

5. A partial denture comprising a downwardly concave tooth carrierfitting over the alveolar ridge of an edentated jaw portion, at leastone elongated sleeve substantially horizontally imbedded in said carrierfor posifltioning alongside said ridge, a flexible wire projecting fromsaid sleeve to the exterior of said carrier for attachment to anexternal support on the jaw and having a concealed extremity receivedwith lateral clearance in said sleeve, and spring means in said sleevebearing upon the latter and upon said wire with an inwardly directedbiasing force, said sleeve and said wire being provided with coastingformations for maintaining said spring means under stress by limitingthe inward displacement-of said wire by said biasing force, theprojecting portion of said wire being withdrawable from said carrieragainst said biasing force for enabling limited yielding of said carrierto a force tending to separate it from said support.

6. A partial denture as defined in claim 5 wherein said sleeve isprovided with an internal abutment, said spring sleeve, therebyconfining said coil spring to a region substantially shorter than saidsleeve and providing a region of increased lateral mobility for saidwire between said abutment and the end of said sleeve facing saidsupport.

10. A partial denture as defined in claim 6 wherein said concealedextremity is provided with a threaded end portion and with a nut screwedonto said end portion in contact with said coil spring, said coactingformations including the tip of saidvthreaded end portion and a setscrew threaded into said sleeve for contact with said tip.

11. A partial denture comprising a downwardly concave tooth carrierfitting over the alveolar ridge of an edentated jaw portion, a pair ofelongated sleeves substantially horizontally and mutually parallelimbedded in said carrier for positioning alongside said ridge onopposite sides thereof, a flexible wire projecting from each of saidsleeves to the exterior of said carrier for attachment to an externalsupport on the jaw and having a concealedextremity received with lateralclearance in the sleeve, and spring means in each sleeve bearing uponthe latter and upon said wire with an inwardly directed biasing force,each sleeve and the corresponding wire being provided with coactingformations for maintaining said spring means under stress by limitingthe inward displacement of said wire by said biasing force, theprojecting portion of said wire being withdrawable from said carrieragainst said biasing force for enabling limited yielding of said carrierto a force tending to separate it from said support.

12. A partial denture comprising a downwardly conca-ve tooth carrierfitting over the alveolar ridge of an edentated jaw portion, at leastone elongated sleeve substantially horizontally imbedded in said carrierfor positioning alongside said ridge, a flexible wire projecting fromsaid sleeve to the exterior of said carrier for attachment to anexternal support on the jaw and having a concealed extremity receivedwith lateral clearance in said sleeve,

said sleeve and said wire being provided with coacting formations formaintaining said spring means under stress by limiting the inwarddisplacement of said wire by said biasing force, the projecting portionof said wire being withdrawable from said carrier against said biasingforce for enabling limited yielding of said carrier to a force tendingto separate it from said support, anchor means engageable with saidexternal support, and hinge means pivotally linking said projectingportion with said anchor means, said hinge means having a pivotal axissubstantially transverse to said sleeve.

13. A dental prosthesis comprising a pair of partial dentures and acurved middle portion, said partial dentures including two downwardlyconcave tooth carriers fitting over diflerent edentated parts of thealveolar ridge of a jaw and being interconnected by at least oneflexible wire having respective extremities anchored therein, saidmiddle portion forming a sheath around an intermediate part of saidwire; spring means in said carriers engaging said extremities with aninwardly directed biasing force; and abutment means rigid with saidcarriers for maintaining said spring means under stress by limiting theinward displacement of said extremities by said biasing force, saidpartial dentures being limitedly separa'ble from said middle portionagainst said biasing force. 14. A dental prosthesis comprising a pair ofpartial dentures and a curved middle portion, said partial denturesincluding two downwardly concave tooth carriers fitting over differentedentated parts of the alveolar ridge I of a jaw and beinginterconnected by at least one flexiblewire having respective pin-shapedextremities anchored therein, said middle portion forming a sheatharound an '7 8 intermediate part of said wire; coil springs in saidcarriers Refei'ences Cited by the Examiner engaging said extremitieswith an invi ardly directed bias- UNITED STATES PATENTS mg force;sleeves in said carriers forming housings around said coil springs andsurrounding said pin-shaped ex- 2,748,480 6/1956 Welssman 325 tremitieswith clearance; and abutment means rigid with 5 FOREIGN PATENTS saidsleeves for maintaining said springs under stress by i limiting theinward displacement of said extremities by 539,994 8/1955 Belgiumsaidbiasing force, said partial dentures being limitedly RICHARD A. GAUDET,Przmary Exammer.

separable from said middle portion against said biasing ROBERT E.MORGAN, Assistant Examiner.

force. 10

3. A PARTIAL DENTURE COMPRISING A DOWNWARDLY CONCAVE TOOTH CARRIEDFITTING OVER THE ALVEOLAR RIDGE OF AN EDENTATED JAW PORTION, ANELONGATED FLEXIBLE ELMENT PROJECTING ENDWISE FROM SAID CARRIER FORATTACHMENT TO AN EXTERNAL SUPPORT ON THE JAW, SPRING MEANS IN SAIDCARRIER ENGAGING SAID ELEMENT WITH AN INWARDLY DIRECTED BIASING FORCE,AND ABUTMENT MEANS RIGID WITH SAID CARRIER MAINTAINING SAID SPRING MEANSUNDER STRESS BY LIMITING THE INWARD DISPLACEMENT OF SAID ELEMENT BY SAIDBIASING FORCE, THE PROJECTING PORTION OF SAID ELEMENT BY SAID BIASINGFORCE, FROM SAID CARRIER AGAINST SAID BIASING FORCE FOR ENABLING LIMITEDYIELDING OF SAID CARRIER TO A FORCE TENDING TO SEPARATE IT FROM SAIDSUPPORT.